He often is delegated the de-facto leader in a variety of circumstances due to his collected nature, which is a position that he doesn't exploit to his power, instead using it to defend his group and protect them.
However, Javi was overpowered by his brother David in their fight, being tackled to the ground and choked with a wrench despite initially holding his own. In both scenarios, Javi proves to be a capable combatant, managing to knock out Lonnie after a brief struggle and successfully disarmed Eli despite him attempting to stab him with a blade. Javi is portrayed in accordance to the player's choices, though in almost all circumstance he takes the position of an arbitrator and the voice of reason, deliberating between equally viable options in a manner that seeks to disarm any opposition within or outside of his group, such as when Clementine and Eli get into an altercation over void bullets where he can either attempt to support Clementine or ask her to calm down, or when his family gets caught using supplies that belong to the New Frontier and he must attempt to negotiate.